Various types of ultrasonic handpieces are utilized for surgical applications, for example, ophthalmic surgery for the removal of cataracts or other tissue. Typically, such handpieces use some type of vibrating transducer, such as of the magnetostrictive or piezoelectric type, which converts electrical energy into mechanical energy. The mechanical energy is used to vibrate a tip, or needle, of the handpiece and the tip distal end emulsifies the tissue with which it comes into contact. The tip is often of a configuration, such as having a hollow interior, to provide a passage for aspiration (evacuation) of the emulsified tissue to a line in the handpiece to be conveyed to a disposal container. The handpiece also often has a line for providing irrigation fluid to the operating site.
It is always an object to improve the overall efficiency of the handpiece and expand its use. A typical ultrasonic handpiece uses a standard tip with an inner aspiration fluid flow passage and has uniform inner and outer diameters along its length. In U.S. Pat. No. 5,242,385, granted on Sep. 7, 1993 to Igor Strukel and assigned to the assignee of the subject application, an improved ultrasonic handpiece and tip are disclosed. The handpiece, which is of the magnetostrictive type, utilizes various improvements in lamination structure to increase the efficiency of the conversion of the electrical to mechanical energy. The patent also discloses a novel tip which is marketed by Surgical Design Corporation of Long Island City New York as the COBRA tip.
The COBRA tip of the aforesaid patent has a distal end section with a circular outer surface that is enlarged relative to the remainder of the tip. The enlarged end section includes the terminal end of the aspiration passage that can be of the same or different diameter from the passage of the remainder of the tip. The exposed end of the tip enlarged distal end section contacts the tissue at the operating site and some of it is drawn into the aspiration passage of the end section by the handpiece evacuation force to be emulsified by the tip vibratory energy. To improve the transfer of the mechanical vibratory energy produced by the handpiece to the tip, the interior of the tip enlarged distal end section preferably is formed of at least two portions of different diameter which are connected by a transition section. This defines at least one interior angle between adjacent ends of the sections of different diameters from which vibratory energy emanates to be more effectively directed, or focused, to effect the tissue emulsification within the aspiration passage. U.S. Pat. No. 5,213,569 to Peter Davis, granted May 25, 1993 discloses a tip whose distal end face end is shaped, by being dished out, to focus the ultrasonic energy at a point exterior of the tip. The outer surface of the tip distal end is circular and the tip end face can be either transverse or at angle to the tip longitudinal axis.